L.L.
Congrats J.! I have a 2 mo. old and a 23 mo. old so I know exactly how you are feeling!
The gift is a great idea. We actually brought a couple of gifts to the hospital- some small things (a stuffed kitty, some books). So when my 21 mo. old came to the hospital to see mommy I was not holding the baby (some people had recommended leaving the baby in the bassinet at that time) and I had her crawl right up on my bed to give me a hug- then I gave her a couple of presents- one from the baby, one from me. You can also do the slide thing a couple of days later (quite frankly, at that age I don't think they care if the presents are "from" the baby or you as long as there are presents!! LOL).
There are also a couple of great picture books about bringing a new baby home- We got "I'm a Big Sister" by Joanna Cole - our daughter loved the book and loves it even more now that the baby is here- if you do a search on Amazon on "big brother" or "big sister" you'll find a handful of great picture books.
All that said- there were some tantrums and still are on some days, but the adjustment has gone really well for us- SO much better than I had expected and I hope it will for you too. Our older one loves to give her sister kisses, put her paci in her mouth, get diapers for mommy, etc.- anyway they can be helpful, let them help! I had painted a much worse scenario in my mind than we actually had-